Rod and sabot assembly

ABSTRACT

The invention relates to an improved rod and sabot assembly comprising a pusher type rod sabot or carrier which is full caliber constructed and functions in the normal manner to launch sub-caliber rod projectile penetrators from conventional smooth bore gun tubes. The inventive improvement obviates the flight perturbation of such penetrators attending the use of conventional longitudinally halved sabots which bear on the stabilizer cone by a construction which extends the sabot halves to bear on a rearwardly disposed full caliber pusher-spacer plate.

United States Patent Baldini 51 May 16, 1972 [54] ROD AND SABOT ASSEMBLY [72] Inventor: Luigi F. Baldini, Elkins Park, Pa.

[73] Assignee: The United States of America as represented by the Secretary of the Army [22] Filed: Sept. 18, 1970 [21] Appl.No.: 73,340

[52] U.S. Cl. ..102/93, 102/D1G. 7

[51] Int. Cl ..F42b 13/16 [58] Field otSearch ..102/93,52, DIG. 7,91

[56] References Cited UNITED STATES PATENTS 620,400 2/1899 Ahrens ..102/93 2,306,140 12/1942 Reed 102/93 3,125,957 3/1964 Lipinski 102/93 X 3,148,472 9/1964 I-Iegge et al. ...l02/93 X 3,262,391 7/1966 ShOber ..102/93 3,585,934 6/1971 Mueller 102/93 FOREIGN PATENTS OR APPLICATIONS 1,262,830 3/1968 Germany ..102/93 Primary Examiner-Robert F. Stahl Attorney-Harry Saragovitz, Edward J. Kelly, Herbert Berl and Sheldon Kanars 57] ABSTRACT The invention relates to an improved rod and sabot assembly comprising a pusher type rod sabot or carrier which is full caliber constructed and functions in the normal manner to launch sub-caliber rod projectile penetrators from conventional smooth bore gun tubes. The inventive improvement obviates the flight perturbation of such penetrators attending the use of conventional longitudinally halved sabots which bear on the stabilizer cone by a construction which extends the sabot halves to bear on a rearwardly disposed full caliber pusher-spacer plate.

20 Claims, 13 Drawing Figures PATENTEDMAY 16 m2 SHEET 2 BF 2 FIG.6A.

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INVIiH'fHR, LUIGI BALDINI MA 4 2W WJ IZQ W M l- 4% Km ATTORNEYS! ROD AND SABOT ASSEMBLY The invention described herein may be manufactured, used, and licensed, by or for the Government for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improved rod sabot assembly and, particularly, to a rod and sabot assembly comprising an improved pusher type, long rod sabot which is full caliber constructed and functions to launch sub-caliber rod projectile penetrators from smooth bore gun tubes.

2. Description of the Prior Art The employment of long rod projectiles as target penetrators has been going on since time immemorial, as evidence such primitive weaponry as the bow and arrow, the spear, and the dart-blowgun. Of more recent vintage, long rod penetrators have been used experimentally in modern small arms, artillery and other types of munitions in the course of investigations wherein the penetrators in sub-caliber form were launched from smooth bore gun tubes by means of full caliber discarding pusher type sabots or carriers.

In general, where the l/d ratio is not greater than 5, prior art spin stabilization techniques permit the obtention of useful data." The latter term is defined herein as data obtained within a short range (50 feet or less) from the launching of a rod penetrator having an in-flight angle of yaw of less than 3 and a point of impact predictable within a distance equal in length to approximately three times the rod diameter. However, the prior art has failed to provide alternate stabilization techniques which can provide the useful data obtained with spin stabilization.

Where the l/d ratio exceeds the problem of spin stabilization is increasingly complex and the prior art techniques fail to satisfactorily provide a solution for launching from a gun. Therefore the method of stabilization is to attach to the rod a drag cone or a fin for stabilization. In the past, neither of these three methods or any combination of them has provided useful data (as defined above). This is evident from prior investigative data showing that where the l/a ratio exceeds 5 the incidence of useful data obtention by any type of stabilization is only 30 to 40 percent. Thus, the investigative time and effort expended in 60 to 70 percent of the cases heretofore has been a total loss.

SUMMARY OF THE INVENTION In general, the present invention is directed to an improvement for obviating flight perturbation of a rod penetrator in a rod and sabot assembly adapted for launching from a smooth bore gun tube comprising a sub-caliber rod drag stabilization means attached to said rod rearwardly thereof, a full caliber longitudinally halved sabot substantially encasing said rod and attached drag stabilization means and arranged and constructed for in-flight separation therefrom, and an obturator of at least full caliber at the rearward end of said assembly, wherein the improvement comprises a partially split pusherspacer plate comprising a full caliber portion abutting said obturator, a sub-caliber portion abutting said rod and attached drag stabilization means, and a shoulder therebetween, and wherein said sabot extends rearwardly encasing the subcaliber portion of said pusher-spacer plate and abutting said shoulder, the arrangement and construction being such that the sabot halves bear on said pusher-spacer plate during said in-flight separation.

The conceptual basis for the invention resides in part in the recognition of the problem that excess yaw, i.e., greater than 3, at short ranges, i.e., less than 50 feet, is attributable essentially to the unbalance produced by the applied torque of the separation of the sabot from the rod or attachments thereto, e. g., drag stabilization means. Angle of yaw is defined in Elements of Ordnance by Thomas J. Hayes, pages 406-419. Further basis resides in the provision of a construction which permits the applied torque of such separation to be transmitted to a component other than the rod or its attachments, e.g., a spacer-pusher plate, thereby permitting the rod which has been launched in a straight line to continue moving along said straight line until it is acted on by some external force, in accordance with Newtons first law.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal plan view of an embodiment of the invention,

FIG. 2 is an end view of the obturator of FIG. 1,

FIG. 3 is a forward end view of the spacer-pusher plate of FIG. 1,

FIG. 4 is a longitudinal view in cross-section of the rod-stabilizer cone assembly of FIG. 1,

FIG. 5 is a rearward end view of the sleeve of FIGS. 1 and 4,

FIGS. 6a and 6b are longitudinal plan and forward end views of the stabilizer cone of FIG. 4,

FIG. 7 is a longitudinal view in cross-section of the sabot halves of FIG. 1,

FIG. 8 is a rearward end view of the sabot halves of FIG. 7, and

FIGS. 9 through 12 are alternate embodiments of the spacer-pusher component depicted in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention may be readily understood and practiced by recourse to the several views of the drawing in conjunction with the following detailed description explanatory thereof. Throughout the several views of the drawing like reference numerals are employed to indicate like components.

FIG. 1 depicts in longitudinal plan view, an improved rod and sabot assembly illustrative of a preferred embodiment of the invention. The embodiment shown comprises a cylindrical rod 10, having an optionally pointed forward end and a sleeve 12 about its rearward end. Rod 10 may be made of high density material, e. g., tungsten, steel, or other penetrating materials depending upon the target to be defeated. Sleeve 12 is preferably attached to rod 10 by a fillet joint 14 of brazing material and is provided with external threads 16, the latter being more readily observed in FIG. 5. A stabilizer cone 18, preferably comprised aluminum, is attached to the rearward end of rod 10 for the purpose of providing inflight drag stabilization. As shown in FIGS. 6a and 6b, stabilizer cone 18 is provided with a rearwardly opening recess 20 adapted to accommodate sleeve 12 and fillet joint 14 and having walls provided with internal threads 22 for threaded engagement with external threads 16 of sleeve 12. Stabilizer cone 18 is provided with a centrally positioned passageway 24 joining the floor 26 of recess 20 with the apex of the cone-shaped structure, whereby rod 10 may readily be attached thereto by inserting the forward end of rod 10 through recess 20 and passageway 24 and slidably drawing rod 10 therethrough until threads 16 and 22 meet and then screwing the respective components together as shown in FIG. 4.

The rod-stabilizer cone assembly of FIG. 4 is shown in FIG. 1 encased in a longitudinally halved sabot 26, preferably made of phenolic impact molding material containing cotton fabric as a filler, having a full caliber outside diameter. The inventive construction differs significantly from the prior art in that the rod-stabilizer cone assembly when seated in sabot 26 is substantially advanced therein, as shown in FIG. 1. Thus, the assembly of FIG. 1 depicts the sabot halves 26 extending rearwardly substantially beyond the rearward end of the rod-stabilizer cone assembly. These sabot extensions 28 bear on a pusher-spacer plate 30 disposed rearwardly of the rod-stabilizer cone assembly of FIG. 4. Pusher-spacer plate 30 is preferably made of aluminum or an alloy thereof, e.g., 2024T4, and comprises a full caliber portion 32 providing a shoulder 34 upon which the ends of sabot extensions 28 bear and a sub-caliber portion 36 encased by sabot extensions 28 and extending forwardly from shoulder 34. Pusher-spacer plate 30 is almost completely longitudinally halved by full diameter, coaxial slot on slit 30. Where rod set-back is a problem, it is contemplated to provide a separate pusher plate (not shown) of a harder material, e.g., steel, between the pusher-spacer plate 30 and the rod and attached drag stabilization means. The preferred sabot construction of FIG. 1 is depicted more clearly in FIGS. 7 and 8 while FIG. 3 provides a clear view of the forward end of pusher-spacer plate 30. An obturator 38, as shown in FIGS. 1 and 2, of a material such as neoprene or Lexan (a trademark of the General Electric Co. employed to designate thermoplastic cabornate-linked polymers produced by reacting bisphenol A and phosgene) is disposed rearwardly of pusher-spacer plate 30 to prevent gas leakage.

While the pusher-spacer plate 30, discussed heretofore, is a preferred embodiment, other embodiments, e.g., as depicted in FIGS. 9 through 12, may be employed in the inventive rod and sabot assembly with similar results and are contemplated within the scope of the invention. FIGS. 9 through 12 depict pusher-spacer components constructed of separate plates. FIG. 9 shows a two plate construction employing a full caliber steel plate 33 and a sub-caliber steel plate 35. FIG. 10 shows a three plate construction similar to that of FIG. 9 but employing an additional sub-caliber steel plate 37. FIG. 11 depicts a construction similar to that of FIG. 10 but employing a subcaliber rubber plate 39 in lieu of sub-caliber steel plate 37. FIG. 12 depicts a construction similar to that of FIG. 10 but employing a sub-caliber rubber plate 39 in lieu of sub-caliber steel plate 35. Rubber plates 39 are employed for their buffer or shock absorbing quality.

In practicing the invention, the rod and sabot assembly of FIG. 1 is inserted in a smooth bore gun tube. A propellant charge is placed behind this assembly and ignited or fired. The entire assembly moves down the smooth bore gun tube as a unit. At the end of the gun tube, assuming the launch is being made into air or some type of atmosphere which will produce some drag, the front cone 27 of the sabot facilitates separation of the longitudinal halves. The air applies a perpendicular force component to the direction of motion of the projectile and this force component causes a torque to be applied to the pusher-spacer plate and the sabot at the rear. The resultant force may produce a complete rupture in the already partially split, pusher-spacer plate and cause it to separate into two halves, and may aid in the separation of the sabot from the rod-stabilizer cone assembly without the former touching the latter. Since the rod-stabilizer cone assembly is traveling in a straight line in the gun tube, it continues to travel straight (with less than a total angle of yaw of 3 because it is not acted on by some external force. The external force produced by the sabot and which acts on the rod assembly in the prior art designs does not occur here. The sabot in the present invention does not tip rod 10 as is done in the prior art designs because the rearward end of the rod-stabilizer assembly is seated in a substantially advanced position within the sabot. Since the rod is not tipped, the result is stable flight with less than 3 of yaw anywhere from the muzzle of the gun outward.

In the course of the investigation leading to the present invention, approximately 500 improved rod and sabot assemblies produced in accordance with the teachings herein were successfully tested over a velocity range and in all cases useful data" was obtained. It was also found that accuracy exceeded that obtained with standard spin stabilized cal. 30 and cal. 50 projectiles. The rod penetrators tested had densities that varied from about 0.283 lbs/in to about 0.630 lbs/in. In general, the rod penetrators had an l/d ratio of and were launched from a 12 foot long, 20mm smooth bore barrel.

While the invention has been described and disclosed in connection with various specific embodiments thereof, it is understood that no limitations or restrictions are intended thereby, the invention being able to accommodate rods of any length to diameter ratio and applicable to any gun caliber (or size), and that said embodiments are merely indicative of the best mode of practicing the invention, the embodiments thereof in which an exclusive property or privilege is claimed being defined as follows in the appended claims.

Iclaim: 1. In a rod and sabot assembly adapted for launching from a smooth bore gun tube comprising a sub-caliber rod, drag stabilization means attached to said rod rearwardly thereof, a full caliber, longitudinally halved sabot substantially encasing said rod and attached drag stabilization means and arranged and constructed for in-flight separation therefrom, and a full caliber, obturator at the rearward end of said as sembly, the improvement for obviating flight perturbation of said rod comprising, a pusher-spacer plate between said assembly and said obturator, said pusher-spacer plate comprising a full caliber portion abutting said obturator, a sub-caliber portion abutting said rod and attached drag stabilization means, and a shoulder therebetween, and wherein said sabot extends rearwardly encasing the sub-caliber portion of said pusher-spacer plate and abutting said shoulder,

the arrangement and construction being such that the sabot halves bear on said pusher-spacer plate during said in-flight separation.

2. An assembly according to claim 1 wherein said rod has a length-todiameter ratio in excess of5.

3. An assembly according to claim 1 wherein said rod extends forwardly beyond said sabot.

4. An assembly according to claim 1 wherein said drag stabilization means comprises a cone-shaped structure with its base rearwardly disposed.

5. An assembly according to claim 4 including a threaded sleeve brazed to the rearward end of said rod, said coneshaped structure being provided with a rearwardly opening recess adapted to receive said sleeve in threaded engagement and a centrally positioned passageway joining the floor of said recess to the apex of said cone-shaped structure, said passageway being adapted for the slidable insertion of said rod.

6. An assembly according to claim 5 wherein said sleeve is attached to said rod by a fillet joint and said excess is adapted to accommodate said fillet joint.

7. An assembly according to claim 4 wherein said coneshaped structure comprises aluminum.

8. An assembly according to claim 1 comprising a pusher plate between said pusher-spacer plate and said obturator, said pusher plate comprising harder material made preferably from an aluminum alloy than said obturator.

9. An assembly according to claim 8 wherein said pusher plate comprises steel and said obturator comprises neoprene.

10. An assembly according to claim 1 wherein said pusherspacer plate is of multi-component construction each of said full caliber and sub-caliber portion comprising at least one plate.

11. An assembly according to claim 10 wherein said full caliber and sub-caliber plates comprise steel.

12. An assembly according to claim 11 including a shock absorber plate between said full caliber and sub-caliber portions and having the same caliber as said sub-caliber portions.

13. An assembly according to claim 12 wherein said shock absorber plate comprises rubber.

14. An assembly according to claim 11 including a shock absorber plate between said sub-caliber portion and said assembly and having the same caliber as said sub-caliber portion.

15. An assembly according to claim 14 wherein said shock absorber plate comprises rubber.

16. An assembly according to claim 1 wherein said sabot comprises a phenolic impact molding material.

17. An assembly according to claim 16 wherein said phenolic impact molding material includes a cotton fabric filler.

said pusher-spacer plate being such as to permit in-flight separation of the longitudinal halves thereof.

19. An assembly according to claim 18 wherein said pusherspacer plate comprises aluminum.

20. An assembly according to claim 19 including a steel pusher plate between said pusher-spacer plate and said rod.

F k 1F 

1. In a rod and sabot assembly adapted for launching from a smooth bore gun tube comprising a sub-caliber rod, drag stabilization means attached to said rod rearwardly thereof, a full caliber, longitudinally halved sabot substantially encasing said rod and attached drag stabilization means and arranged and constructed for in-flight separation therefrom, and a full caliber, obturator at the rearward end of said assembly, the improvement for obviating flight perturbation of said rod comprising, a pusher-spacer plate between said assembly and said obturator, said pusher-spacer plate comprising a full caliber portion abutting said obturator, a sub-caliber portion abutting said rod and attached drag stabilization means, and a shoulder therebetween, and wherein said sabot extends rearwardly encasing the sub-caliber portion of said pusher-spacer plate and abutting said shoulder, the arrangement and construction being such that the sabot halves bear on said pusher-spacer plate during said in-flight separation.
 2. An assembly according to claim 1 wherein said rod has a length-to-diameter ratio in excess of
 5. 3. An assembly according to claim 1 wherein said rod extends forwardly beyond said sabot.
 4. An assembly according to claim 1 wherein said drag stabilization means comprises a cone-shaped structure with its base rearwardly disposed.
 5. An assembly according to claim 4 including a threaded sleeve brazed to the rearward end of said rod, said cone-shaped structure being provided with a rearwardly opening recess adapted to receive said sleeve in threaded engagement and a centrally positioned passageway joining the floor of said recess to the apex of said cone-shaped structure, said passageway being adapted for the slidable insertion of said rod.
 6. An assembly according to claim 5 wherein said sleeve is attached to said rod by a fillet joint and said excess is adapted to accommodate said fillet joint.
 7. An assembly according to claim 4 wherein said cone-shaped structure comprises aluminum.
 8. An assembly according to claim 1 comprising a pusher plate between said pusher-spacer plate and said obturator, said pusher plate comprising harder material made preferably from an aluminum alloy than said obturator.
 9. An assembly according to claim 8 wherein said pusher plate comprises steel and said obturator comprises neoprene.
 10. An assembly according to claim 1 wherein said pusher-spacer plate is of multi-component construction each of said full caliber and sub-caliber portion comprising at least one plate.
 11. An assembly according to claim 10 wherein said full caliber and sub-caliber plates comprise steel.
 12. An assembly according to claim 11 including a shock absorber plate between said full caliber and sub-caliber portions and having the same caliber as said sub-caliber portions.
 13. An assembly according to claim 12 wherein said shock absorber plate comprises rubber.
 14. An assembly according to claim 11 including a shock absorber plate between said sub-caliber portion and said assembly and having the same caliber as said sub-caliber portion.
 15. An assembly according to claim 14 wherein said shock absorber plate comprises rubber.
 16. An assembly according to claim 1 wherein said sabot comprises a phenolic impact molding material.
 17. An assembly according to claim 16 wherein said phenolic impact molding material includes a cotton fabric filler.
 18. An assembly according to claim 1 wherein said pusher-spacer plate is almost completely longitudinally halved by a full diameter slit passing through the axis of said plate and extending from the face of said sub-caliber portion abutting said rod and attached drag stabilization means to a plane passing through said full caliber portion parallel to the face thereof abutting said obturator, the arrangement and construction of said pusher-spacer plate being such as to permit in-flight separation of the longitudinal halves thereof.
 19. An assembly according to claim 18 wherein said pusher-spacer plate comprises aluminum.
 20. An assembly according to claim 19 including a steel pusher plate between said pusher-spacer plate and said rod. 